PREDICTING METEOR SHOWERS
very earliest developments at the Stonehenge – dating
from 3500 - 2800B.C. – were used to predict when meteor showers were to occur.
The stars, the
planets, the moon and the sun 5000 years ago would all look much the same as
today, but not the comets and meteors.
source of this dust is believed to be a broken-up giant comet, which has spawned
a huge complex of material in the inner solar system including numerous
asteroids, meteoroid streams, the comet
tracking of the Earth’s orbit indicates that great meteor storms will then
occur every few years in epochs lasting for a few centuries. There will be pairs
of these epochs separated by 300 – 500 years, followed by a gap of about 2500
– 3000 years before the next pair occurs. These timings fall out from the
celestial mechanics, involving some quite complicated calculations.
The daytime Taurid
showers are active (to some extent) in the present epoch, they would not have
been peaking in summer when Stonehenge I was built. The dates and the radiants
of the Taurid Complex showers were not the same 4500 to 5000 years ago, due to
With the present
system of leap years (according to the Gregorian calendar), after about 1600
years, we will be close to half a day out and an adjustment might be necessary.
This is due to the
difference of 0.014173 days per annum between the sidereal year (according to
the stars) and the tropical year (according to the seasons). Thus, there is a
slippage between them of close to 14 days per millennium, this is being termed
the precession of the equinoxes. This means that a meteor shower occurring on 16
April 2000 will occur a week later on 16 April 2500 (using the tropical
Apart from the date
of a meteor shower being shifted by the precession of the equinoxes, precession
of the meteoroid stream orbit caused by planetary perturbations will also alter
the date on which a shower occurs. The precession of the streams means that the
shower radiants would be in different constellations from those occupied
When the appropriate
precession rates, Taurids would have peaked in March in 3000 B.C., about 110
days earlier than they do today; that is, 22 days earlier per millennium.
Around 5000years ago,
the Southern Taurids would peak in mid-July, but with the activity starting
The daytime showers
have radiants very close to the sun. As for the night-time showers, the radiants
are in precisely the opposite direction of those of the daytime: close to the
antipodal point of the Sun, but about an hour wast of it. Sunrise is close to
3:50 A.M. around midsummer at Stonehenge, so the shower radiant would rise at
about 5 P.M. while there is still around 4 hours of daylight left.
The meteor rate would
gradually rise as dusk passed, continuing to grow until the radiant reached its
highest point in the sky, reaching a crescendo around midnight which would
continue for the next 3 to 4 hours until dying away as the Sun rises and drowns
out all but the brightest fireballs visible in daylight. This desire to see the
Sun rising provides an explanation for the alignment of the main axis toward the
northeast, the Heel Stone and its twin forming a gap through which the Sun would
The Taurid stream,
with an orbital period of about 3.3 years, the cycle of storms/detonations would
be about 10 years; the group of large objects would miss the Earth on 2 out of 3
passes through our orbit, but hit on the 3rd. it would be simpler to
hypothesize that the meteor storms occurred every 19 years, to fit in with the
apparent cycle that Stonehenge III follows.
The main axis of the
Stonehenge is aligned with where the Sun rose on Midsummer Day, seeming to chase
away the meteors whose radiant
had risen nearby about 11 hours earlier. However, the Heel Stone and its twin,
which may or may not have been present, mark that axis. (recall that a
“hole” which was refilled was being found near the Heel Stone).
circular bank and the ditch of Stonehenge I
was complete, forming an enclosure. Although that bank is barely shin-high now,
when it was built, it was just over head-high. Its purpose could have been to
form a level, artificial horizon for observers inside. If the point of
was to monitor meteor rates in order to predict when storms were due, obviously
a dark, protected area would have been necessary.